1. Field of the Invention
This invention relates to apparatus for indicating air traffic and terrain collision threats to an aircraft.
2. Related Art
Air traffic advisory are known which are able to provide a warning of potential collision courses with neighboring aircraft. Such known systems monitor the speed and flight path of other aircraft with respect to the aircraft in question and provide advisory warnings when any aircraft is predicted to pass within a predetermined distance of the aircraft in question.
Terrain advisory systems are also known which interrogate a terrain database with respect to the aircraft flight path and provide advisory warnings when the aircraft flight path is predicted to take the aircraft into a hazardous situation. These known systems operate independently of each other and do not coordinate traffic and terrain advisory warnings. It is therefore possible for a terrain advisory system to produce a warning requiring a climb recover maneuver which is potentially dangerous due to the unknown presence of air traffic above the aircraft in question. It is also possible with a known stand-alone traffic advisory system for it to produce a warning requiring the aircraft to descend into a hazardous terrain situation.
There is thus a need for a generally improved apparatus for indicating air traffic and terrain collision threats to an aircraft which takes into account both terrain and air traffic conditions.
According to a first aspect of the present invention, there is provided apparatus for indicating air traffic and terrain collision threats to an aircraft, including traffic advisory means for monitoring the position and behavior of air traffic in the vicinity of an in-flight aircraft provided with the apparatus and for generating a warning and/or avoidance signal for air traffic predicted to be on a collision course with the in-flight aircraft, terrain advisory means for monitoring the position and behavior of the in-flight aircraft relative to terrain in the vicinity of the aircraft flight path and for generating a warning and/or avoidance signal for terrain features predicted to provide a collision threat on the aircraft flight path, and interactive means for receiving traffic warning and/or avoidance signals from the traffic advisory means and terrain warning and/or avoidance signals from the terrain advisory means, comparing said signals and generating a combined warning and/or advisory signal which indicates an action for the aircraft which avoids both air traffic and terrain collisions.
Preferably, the traffic advisory means includes a transponder for receiving signals relating to the absolute and/or relative positions of air traffic in the vicinity of the aircraft and a traffic warning and/or avoidance signal generator operable to receive output signals from the transponder, calculate and monitor the position and behavior of air traffic in the vicinity of the aircraft and generate said traffic warning and/or avoidance signal.
Conveniently the traffic warning and/or avoidance signal generator is connectable to a flight management system of the aircraft to receive aircraft operating information therefrom.
Advantageously, the terrain advisory means includes a store of representations of terrain and obstacles in and around the aircraft flight path, a search logic device for retrieving data from the store within a predetermined latitudinal and longitudinal envelope defined relative to the aircraft position and velocity and a terrain warning and/or avoidance signal generator operable to receive, from a navigation system of the aircraft, signals representative of the latitude, longitude and altitude of the aircraft, calculate the predicted aircraft ground flight path and generate the terrain warning and/or avoidance signal.
Preferably, the terrain warning and/or avoidance signal generator includes a comparator for comparing the predicted aircraft ground flight path with the worst case terrain profile so that the terrain warning and/or avoidance signal is issued if either the predicted aircraft altitude falls below a predetermined minimum clearance height at any point along the predicted ground flight path or if intersection with the terrain is predicted to be less than a predetermined time to impact.
Conveniently the interactive means interlinks and forms part of the traffic warning and/or avoidance signal generator and the terrain warning and/or avoidance signal generator.
Advantageously, the apparatus includes an auditory warning device and a visual avoidance display device receiving output signals from said traffic warning and/or avoidance signal generator and said terrain warning and/or avoidance signal generator, which warning device additionally feeds an output signal to said display device.